What the ruling actually changed — and what Philippine foreign policy has done with it
The Permanent Court of Arbitration’s July 12, 2016 ruling ran to 501 pages and was unambiguous on every major legal question it addressed. The Philippines’ EEZ rights were valid under UNCLOS. China’s nine-dash line claim had no basis in international law. Mischief Reef, Subi Reef, and Fiery Cross, enlarged through dredging operations that began in earnest in 2013 and fortified with airstrips and missile batteries by 2018, were legally within Philippine jurisdiction. The tribunal did not hedge.
China declared the ruling “null and void” and continued construction.
The question worth asking at ten years is not whether Beijing complied. It did not. The design of UNCLOS arbitration was never predicated on great-power compliance, which is a point that matters more than it is usually given credit for. The sharper question is what the Philippines has done with what it actually won. The record on that is mixed in ways that a decade of official statements has not consistently acknowledged.
Legal legitimacy
UNCLOS was negotiated between 1973 and 1982 by states that understood, with some precision, that the dispute resolution mechanism they were building would not produce enforceable judgments in the way domestic courts do. They signed it anyway, because what the mechanism provides is something different: legal legitimacy, which shifts the burden of justification in every diplomatic setting that follows.
The July 2016 ruling changed the evidentiary baseline for South China Sea disputes in a way that does not expire. Features that China classifies as islands (and which, as islands, would generate EEZ entitlements of their own under UNCLOS Article 121) were reclassified by the tribunal as rocks or low-tide elevations. That classification is now the reference point for every subsequent legal proceeding, diplomatic protest, and multilateral communiqué involving those features. No new legal action is required to invoke it.
The effect on third-party states has been the ruling’s most underappreciated structural consequence. Japan, Australia, the United States, and the European Union were not parties to the arbitration. All of them now routinely cite the ruling in their official positions on South China Sea navigation and overflight rights, positions they would otherwise have had to ground in their own, slower, more politically exposed legal proceedings. The ruling gave third parties a legally precise vocabulary to deploy against China without requiring those states to generate their own findings. For coalition-building purposes, that is leverage the Philippines created for the region, whether or not Manila has used it consistently.
It has not used it consistently.
Invoking the Ruling
The standard critique, that the ruling has been “cheapened” by frequent diplomatic protest, contains a logical error worth correcting before it misleads anyone in a position to act on it.
Under UNCLOS and general principles of customary international law, consistent protest is not optional. A state that fails to formally object to violations of its EEZ rights risks acquiescence: the legal inference that silence implies acceptance. Every protest note the Philippines files with Beijing, however theatrically Beijing dismisses it, performs a specific legal function. It preserves the evidentiary record that the Philippines has never conceded the rights the tribunal confirmed. Stopping those protests would not strengthen the Philippines’ strategic posture. It would quietly erode the legal position the arbitration established.
The distinction that matters is not between protesting and not protesting. It is between pro forma invocation and strategic deployment. Pro forma invocation is the routine, consistent filing that maintains legal standing and generates the documentary record. Strategic deployment is a different instrument with a different purpose and a different audience. Pro forma protests go to Beijing. Strategic invocations are directed at third-party states, multilateral forums, and the institutions where the ruling’s authority compounds over time through repeated, coordinated citation: the UN General Assembly, the IMO, the ASEAN Regional Forum. The Philippines has been diligent about the first. It has been inconsistent about the second.
Each time Manila invokes the ruling strategically, in a joint statement, in an ARF session, in a trilateral with the United States and Japan, without a coordinated multilateral response, it signals to Beijing that the strategic instrument is available cheaply. The signal this sends is not “comply or face escalating pressure.” It is, more precisely, “expect this in every communiqué; adjust response accordingly.” The diplomatic infrastructure that prevents that signal requires something the protest note alone cannot provide: a coalition of states prepared to make China’s non-compliance consistently costly in settings Beijing cares about.
Eroded Legitimacy
The enforcement problem is frequently overstated, and in a way that obscures the real failure.
UNCLOS was never designed to generate enforceable judgments the way domestic courts do. What the arbitration mechanism provides is legal legitimacy of a specific kind: the kind that shifts the burden of justification in diplomatic settings. China now has to explain, repeatedly, why it rejects a tribunal it agreed to in principle when it ratified UNCLOS. That is not nothing.
What eroded that legitimacy was the September 2016 decision by the Duterte administration to explicitly shelve the ruling as part of a diplomatic realignment toward Beijing premised on infrastructure investment. The investment, projected at $24 billion in pledges made during President Duterte’s October 2016 state visit to China, did not materialize at scale. A 2019 IBON Foundation monitoring report found that of 27 infrastructure agreements signed during the period, fewer than a third had reached implementation stage by end-2018. The realignment was asymmetric: the Philippines surrendered legal posture; China pocketed the concession and continued fortifying its positions.
The Marcos administration has corrected course rhetorically, restoring the ruling to official Philippine legal posture by 2023. Whether it has corrected course structurally is what the coalition section below examines.
The Vietnam comparison
Vietnam did not pursue UNCLOS arbitration. This is frequently cited as a strategic miscalculation. Hanoi had overlapping claims with the Philippines on several Spratly features, arguably stronger physical presence on some of them, and chose a combination of quiet diplomacy and bilateral engagement with China rather than formal legal action. The conventional reading holds that Vietnam surrendered the legal legitimacy the Philippines gained.
That reading is accurate as far as it goes. It does not go far enough, and it misleads if taken as an argument that diplomatic restraint alone would have produced better outcomes for Manila.
Vietnam’s operational posture in the South China Sea is not primarily a product of diplomatic temperament. It is backed by a maritime enforcement apparatus that the Philippines does not currently possess. Vietnam’s coast guard has expanded continuously since 2010 and now numbers approximately 10,000 personnel operating a fleet with meaningful blue-water presence. Its maritime militia, fishing vessels operating in coordinated patterns across contested Spratly features, functions as a distributed presence tool that makes the operational cost of displacement higher than Beijing has been willing to pay in that theater. Vietnam also shares a 1,297-kilometer land border with China, which creates mutual economic exposure and land-corridor leverage that have no equivalent in the Philippine geographic position.
In the decade since the PCA ruling, Vietnamese fishing communities have maintained functional access to contested areas in the Spratly group, measured by fleet numbers, catch data, and maritime incident records compiled by the South China Sea Strategic Situation Probing Initiative at Peking University, at rates broadly comparable to the early 2010s. Not because China respects Vietnamese claims (it does not), but because Hanoi calibrated its response with enforcement depth the Philippines has not yet built. The legal record from the arbitration is cleaner on the Philippine side. The operational outcome, measured by what fishermen from each country can actually access at sea, is not straightforwardly in the Philippines’ favor.
The comparison is not an argument against arbitration. It is an argument for being precise about what legal victories purchase and what enforcement capacity they require. The ruling created the legal foundation. Vietnam’s experience suggests the foundation requires a structure built on top of it.
What happened in the ASEAN
Most coverage of the arbitration’s ten-year record focuses on Beijing’s rejection and Manila’s response. The effect on ASEAN’s internal legal dynamics has received less attention, and it is where the ruling’s compounding impact has been most consequential.
Before 2016, ASEAN’s internal debates about South China Sea language were paralyzed by whether specific phrasing implied legal conclusions about sovereignty that member states were not prepared to commit to. The arbitration ruling genericized the legal framework in a specific way: it became possible for member states to reference EEZ rights and UNCLOS compliance without it being read as a bilateral Philippines-China matter. Indonesia’s 2020 diplomatic note to the UN Secretary-General explicitly rejecting Chinese claims near the Natuna Islands cited the tribunal’s reasoning directly, a more assertive legal position than Jakarta had publicly taken since the early 2000s. Malaysia’s 2019 continental shelf submission, which overlapped with Chinese claims in a manner that would have been diplomatically untenable before the ruling provided legal cover, proceeded without triggering the level of bilateral deterioration that Beijing’s pre-2016 behavior had led Kuala Lumpur to anticipate.
The Philippines did not lead that regional legal clarification actively. It created the conditions for it, then did not exploit the opening. That is the missed opportunity — more than the failure to extract compliance from Beijing.
Coalition work
The coalition argument — that the ruling’s value compounds when multiple states invoke it in settings Beijing cares about — is not hypothetical. The architecture to build that coalition is partially constructed. Whether the Philippines is organized to use it is the operational question.
The most developed framework is the US-Japan-Philippines trilateral, which has met at both foreign minister and defense minister levels since 2023 and has issued joint statements that explicitly reference UNCLOS and the 2016 ruling. The Quad Maritime Legal Dialogues — the first held in December 2024, the second in early 2025 — brought together legal specialists from the United States, Australia, India, and Japan to align positions on maritime law questions the South China Sea dispute sits at the center of. The first Quad-at-Sea Ship Observer Mission concluded in July 2025. These are not aspirational documents. They are operational meetings with records.
The Indo-Pacific Partnership for Maritime Domain Awareness, launched at the Quad Summit in May 2022, offers the Philippines access to satellite-based radio frequency data, AIS integration, and the SeaVision common operating picture — the same surveillance tools that make Vietnamese and Indonesian coast guard presence more effective in contested waters. Philippine officials have been invited to participate. Privately, officials have acknowledged that challenges remain on adoption and usage, including compatibility issues that the DFA and PCG have not resolved publicly. The EU’s IORIS platform, part of the CRIMARIO II program, has extended coverage to the Indo-Pacific and specifically invited Philippine participation. The Expanded ASEAN Maritime Forum, which the United States co-chairs alongside Indonesia and India at the ARF intersessional level, is the multilateral venue where legal citation and operational coordination can be combined.
The framework that most directly addresses the gap between legal posture and operational capacity is the Squad — the US-Japan-Australia-Philippines security grouping that conducts real-time maritime drills and operational signaling in the South China Sea. At the 2025 Raisina Dialogue, AFP Chief of Staff General Romeo Brawner proposed expanding it to include India and South Korea. Whether that expansion proceeds matters less than whether the existing Squad has been integrated into Philippine foreign policy’s strategic use of the ruling — as the operational arm that gives the legal instrument teeth in specific incidents, rather than a parallel track that operates without reference to the arbitration record.
The frameworks exist. What is absent is evidence that the DFA has organized a coherent doctrine for using them in combination — deploying the trilateral and Squad for operational signaling, the Quad Legal Dialogues for legal alignment, the ASEAN forums for regional coalition-building, and the IPMDA and IORIS for the domain awareness capacity that makes enforcement credible. Each framework is being used. None of them appear to be coordinated toward a unified theory of how the ruling compounds in value over the next decade.
The next decade
International legal rulings against great powers do not produce compliance on a timeline that satisfies anyone watching for it. The 1986 ICJ ruling in Nicaragua v. United States took longer than most legal scholars in 1986 predicted before its reasoning became embedded in multilateral frameworks Washington cared about for unrelated reasons. The South China Sea ruling is on a similar trajectory — not dead, not advancing linearly, not dependent on Chinese compliance for its value.
China will not adjust because the ruling says it should. It may adjust, at the margins, if the coalition of states citing the ruling becomes coherent enough and the economic stakes involved — market access, infrastructure finance, security cooperation terms — make continued defiance more costly than marginal adjustment. The Duterte administration demonstrated that Manila’s legal posture is negotiable; reversing that demonstration requires sustained consistency across at least one full additional administration cycle.
The Philippines is a mid-sized state navigating a historically transactional relationship with every major power in the region. That constraint is structural, not a failure of any particular administration. What has changed since 2016 is that the frameworks for building the coalition that makes the ruling costly to ignore are now more developed than they have ever been. The IPMDA exists. The trilateral exists. The Squad exists. The Quad Legal Dialogues exist. The question is whether Philippine foreign policy is institutionally organized to use them in combination — and whether that organization persists when the administration changes.
The ruling is not a trophy. It is not a dead letter. It is a legal instrument of specific, bounded utility whose value depends on what is built around it. The decade that produced it is finished. The decade that tests it has started.
This report draws on the PCA Award of July 12, 2016 (PCA Case No. 2013-19); IBON Foundation infrastructure monitoring data (2019); South China Sea Strategic Situation Probing Initiative fleet and incident records; Indonesia’s UN diplomatic note of June 2020 (No. 126/POL-703/VI/20); publicly available ASEAN Summit and Foreign Ministers’ Meeting joint communiqués, 2016–2025; the 2025 Quad Foreign Ministers’ Meeting joint statement (July 1, 2025); US State Department maritime security commitment statement (September 2025); and Wilson Center analysis of ASEAN maritime domain awareness frameworks (2024). This report was commissioned by the Department of Foreign Affairs for policy discussion purposes. philreport.com’s editorial positions are independent of commissioning agencies. This analysis does not constitute legal advice.